Low-molecular weight liquid crystal compounds are the most representative display materials for flat panel displays and have been widely used in TN mode liquid crystal displays, e.g., for digital watches, and STN mode liquid crystal displays, e.g., for lap-top computers and lap-top word processors. In these displays, "on" (transparent) and "off" (non-transparent) states are controlled by utilizing the phenomenon that the light transmitted through the liquid crystal layer changes its plane of polarization with a voltage applied. Therefore, the devices must have a pair of polarizing sheets to sandwich the liquid crystal layer. Further, an orientation treatment is essentially needed for the liquid crystal layer to have specific orientations.
In recent years, hybrid type liquid crystal display elements have been proposed, in which the low-molecular weight liquid crystal compound is supported in a polymeric binder by dispersion or encapsulation as disclosed, e.g., in U.S. Pat. No. 4,435,047, laid-open International application Sho-58-501631 and JP-A-1-312527 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). In this type of displays, switching between "on" and "off" states, i.e., "transparent" and "scattering" states, is controlled by utilizing the phenomenon that the light transmitted changes its scattering state with a voltage applied. Therefore, the necessity of polarizing sheets as having been used in conventional TN and STN mode liquid crystal display elements can be eliminated, and it is expected to realize brighter display elements. Further, any alignment film is not needed, thus removing the steps involved therefor, such as printing, baking and rubbing of an orientation film, which is expected to bring about great reduction of production cost.
However, because the conventional hybrid type display elements composed of a polymeric binder having maintained therein a low-molecular weight liquid crystal compound need a high driving voltage of from 60 to 100 Vrms, they have a narrow range of application and have found use only as simple light controlling elements (such as light controlling glass). Moreover, they lack in steepness in the voltage v. transmission curve and have no hysteresis characteristics, which disadvantages have made it practically difficult to apply them to wide-area display elements.